1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to image correction, and more particularly, to correcting projected images so that, when images are projected onto a plane from a projector, image distortion is avoided.
2. Description of the Related Art
As is generally known in the art, a display system using a projector displays image frames by projecting them onto a planar screen. When the screen has a hue, however, the color of image frames projected onto the screen is distorted. In addition, when the screen is not completely planar, projected image frames are distorted geometrically due to the uneven screen.
In order to correct the distortion of projected image frames, chromatic and geometric characteristics of the screen must be modeled. Hereinafter, this process will be referred to as “screen estimation.” A related art method for modeling the characteristics of the screen includes the steps of projecting a simple test pattern onto the screen before image frames are projected, photographing the projected pattern with a camera, and comparing the projected pattern with the photographed one. The result of comparison is used to obtain a function regarding the characteristics of the screen. By applying the inverse function of the obtained function to-be-projected image frames the user can watch image frames without distortion resulting from the characteristics of the screen. Pertinent correction technologies are disclosed in the paper “Embedded Entertainment with Smart Projectors” by Bimber, O., Emmerling, A., and Klemmer, T. (IEEE Computer, January 2005, pp. 56-63), as well as in patent publication WO 2005/015490 A2 and U.S. patent application Publication No. 2003-0214510.
Recently, there has been an increasing demand for technology that can correct the distortion of image frames resulting from the characteristics of the screen so that image frames can be projected not only onto projector screens, but also onto other types of projection surfaces (e.g., walls, curtains).
However, related art methods for correcting the distortion of image frames have a problem in that, before correction is performed, a number of simple text patterns must be projected onto the screen and photographed for the purpose of screen estimation. This renders the correction process complicated. In addition, projection of image frames of desired content must be suspended until the correction process is over. Particularly, users will be displeased if the characteristics of the screen vary during the viewing of content, due to movement of the screen or projector, or an illumination change, and the screen must be re-estimated frequently.
Therefore, a technology for estimating a screen while image frames are being projected and without being noticed by the user is needed.